We request funding for a confocal/multi-photon microscope that will serve critical imaging needs of fifteen faculty members, many of whom are interested in the dynamic monitoring of tissue cell and matrix components relying on fluorescence and scattering signals for regenerative medicine, tissue engineering and various disease diagnostic and therapeutic applications. During the last ten years, we have demonstrated the wealth of tissue structural and functional information that can be acquired from non-invasive, high resolution imaging approaches, such as confocal, two-photon excited fluorescence and second harmonic generation microscopy. These studies are leading to new directions that require: a) long-term (multiple hours to days) dynamic monitoring of the same sample, b) monitoring of very fast interactions, c) examination of large fields of view, d) enhanced sensitivity to weak endogenous signals, and/or e) improved imaging penetration depths. These directions cannot be pursued with the one confocal/multi-photon microscope that is available at the Tufts Medford campus that is now over ten years old. The current system was utilized approximately 100 hours/week in 2014, even with strict limits imposed on usage time. This prevents the design of needed studies that require monitoring over several days. In addition, the system is outdated and doesn't allow updates that enable more sensitive detection of the signals that many of the studies described in this proposal rely on. For these reasons, the proposed instrument is expected to fulfill critical microscopic imaging needs. Specifically, the new microscope will enable the performance of long-term or fast, high-resolution optical imaging for numerous projects aiming to solve important biomedical problems spanning the fields of microbiology, cancer biology, metabolomics, and tissue engineering among others. While long-term studies will be enabled simply by the availability of the system, a number of its features are essential in advancing the functional content of the acquired images, including: a) enhanced efficiency, sensitivity and flexibility of fluorescence detection for monitoring weaker and more variable chromophores, b) ability to perform measurements with automated control over the incident intensity during imaging to optimize sample viability and imaging penetration depth, c) more automated examination of thick and wide specimens, and d) faster image acquisition. The multidisciplinary team of investigators represents four different Schools within the Medford and Boston Tufts campuses, demonstrating the significant impact on a broad research spectrum and on student training and education. The PI's main research interests are in the area of high-resolution optical imaging and she has the expertise and technical support to ensure innovative and appropriate use of the equipment. There is newly renovated space to house the instrument, significant institutional support, and a long-term sustainability plan for maintaining and running the microscope. Finally, we have established both an internal and an external advisory board to assist with potential administrative and experimental issues that arise.